As the play clock ticks down and Vick barks out signals, Lewis will peer across the line of scrimmage to glean hints of what Vick might do next. Vick's impact is seemingly limited only by his imagination.

Although Vick is coming off one of his worst games, a four-interception debacle in a narrow win over the Cleveland Browns, the Ravens are aware of the kind of damage the multidimensional passer can inflict.

"It's no secret who this guy is," Lewis said. "This guy is fantastic with the football. We have to play our game. You can't be enamored of what he does. He's Vick, and he's a very, very, very, very special talent, but we are ready to go play a full football game."

Between his strong left arm, sprinter's speed and uncanny knack for making defenders look foolish with electric moves, Vick is a unique figure in the NFL quarterback fraternity.

"He's a guy who can shred you with his arm and his legs," Ravens strong safety Bernard Pollard said.

Defending Vick figures to test the Ravens to their core in terms of demanding athleticism and applying a sound strategy to every snap.

"He's elusive," Ravens coach John Harbaugh said. "He can really throw the ball. You can never underestimate that."

Any lapses of concentration or physical breakdowns against Vick can spell doom for a defense, even a veteran outfit like the Ravens that ranked third in total defense last season and 13th overall this year.

"He's a rare breed," cornerback Cary Williams said of Vick, who has passed for 18,229 career yards and 113 touchdowns with 5,251 yards and 33 touchdowns rushing. "We've got to contain him because he has great arm strength and his running ability is amazing.

"We've got good athletes to match up with him. We're not afraid of him, by any means. It takes all 11 players to stop him."

Should he assign one defender as a designated spy devoted to shadowing Vick wherever he goes?

Or should Pees stick with his 3-4 base alignment, having players carry out normal assignments with an eye toward keeping Vick inside the pocket and away from the perimeter?

Using a spy against Vick typically involves a mobile defender, such as a safety or a fast linebacker, with no pass-coverage, pass-rushing responsibilities or other duties until the football leaves his hands.

"Whether you spy him or not, you take out the integrity of your defense," Lewis said. "You start to compromise it a little bit. If you play the way your defense should be playing, it should take care of itself. Anytime you try to do something extra for one player, no matter who it is, I believe it kind of messes up your scheme of things."

NFL analyst Greg Cosell, a senior producer at NFL Films known for his intense study of game film, isn't an advocate of using a spy on Vick.

"It's a waste of time," Cosell said. "He's a better athlete than anybody you're going to put on him, and you're removing a guy from pressure or from coverage. Some people tell you he's frenetic and live with the one or two big runs. That gets him out of his rhythm and he totally becomes a sandlot player.

"Other people are scared to death of him. So, they just try to gently push the pocket and keep their outside rushers in to keep him boxed in. There's two schools of thought."

Former Washington Redskins safety Matt Bowen says maintaining discipline with defensive ends and outside linebackers is more important than dedicating one defender to Vick.

"I'm never a big fan of spying the quarterback," Bowen said. "If you let Vick outside, that's when that 4.4 speed comes into play. The Baltimore outside linebackers need to get up the field and when they sense they're getting too high, that's when you plant your foot and keep him in that circle. Then, he has nowhere to go. That's when he starts making mistakes."

Against the Browns, Vick completed only 29 of 56 passes for 317 yards and two touchdowns.

"I think you play your defense and don't defend the specific individual," former NFL quarterback Joe Theismann said. "Michael Vick can run faster than anybody you have on your defense. You keep a body in front of him and direct him to your support. You can focus on Michael, but it's LeSean McCoy, their running back, that makes that offense go. He's the piston that drives that engine."

If the Ravens do spy Vick, even occasionally, it would probably involve using Pollard.

"If you're going to spy Michael Vick, you better have that kind of athlete," said Ravens safety Sean Considine, a former Eagles starter who had seven tackles and a sack while playing for the Jacksonville Jaguars against Vick two years ago. "He's as good an athlete as you're going to see in the NFL regardless of position. Obviously, if you're spying a quarterback, you're taking something away from somewhere else. If you worry about Michael Vick scrambling, you're going to have a hole somewhere else. There's a give and take."

Vick has seen every gimmick defense during his 11 years in the NFL.

At this stage of his career, the four-time Pro Bowl selection welcomes the unconventional.

"They might put a spy in the middle, rob the coverage every now and then," Vick said. "For the most part, teams just line up and play. That's the way I like it. That's the way I want it. If they do put a robber in there, it takes somebody out of pass coverage, so we have to exploit that."

Erratic tendencies

The complex dichotomy of Vick was on full display during the Eagles' 17-16 escape over the Browns. Vick admittedly got flustered during a close game and attempted to force the action.

He made throws into heavy coverage, finishing with a 51.0 passer rating and 51.7 percent accuracy.

"Being self-critical, I was just trying to force too many throws," Vick said. "I tried to make something happen when I felt as if we should have already had more points on the board. I just got impatient, tried to rush things and just tried to do too much. I started letting balls go that I should never have thrown.

"What quarterback doesn't have rough games every now and then? People criticize me a little bit more because I'm different, because I play the game different, which is unfair, but I don't really care. The only thing that matters to me is winning and losing."

If not for drops by the Browns' secondary, though, Vick could have easily had more than four interceptions.

For his career, Vick has 76 interceptions and has completed only 55.9 percent of his throws.

Cosell sees the former Virginia Tech star as a fundamentally flawed quarterback.

"While talented athletically, he's never truly mastered the subtle nuances necessary to play the position consistently," Cosell said. "Most people view improvisation as a positive, but it's random and it can be negative. They've tried to make him a dialed-in, disciplined passer and he can throw a beautiful ball, but he's still not particularly quick on progressions. To be a high-level quarterback, you need to understand the defense before the snap.

"I think he has some blind spots as far as not picking up underneath coverage. He's not an anticipation thrower, not really a pocket thrower. Sometimes it looks like the receivers are covered, but he doesn't throw the ball when other quarterbacks would. He's not precise with the ball, and he can make his offensive line look poor at times."

It has been four years since Vick was reinstated to the NFL and joined the Eagles after serving time in federal prison stemming from his role in a dogfighting ring.

Although Vick, 32, has remained out of trouble off the field and by all accounts reformed his life, there still remains room for growth on the field.

"I think Michael is in a maturation stage," Theismann said. "Every quarterback tries to do too much and you really have to fight it when you have the athletic ability Michael has. It's a constant battle.

"He can't get frustrated. He was lucky he didn't have eight interceptions last week. I think he's in desperate need of a good game."

The Ravens have prepared all week for Vick by having backup Tyrod Taylor, a former Virginia Tech player, emulate his mentor on the scout team offense.

And the defense is convinced that Vick will provide a supreme challenge.

"People are always doubting him, and the guy has always bounced back," Pollard said. "Our thing is we have to contain him. He gets paid to play football and to beat us, and we're going to have to do a good job against him."

Personal: Vick and his wife, Kijafa, live in Philadelphia. He has two daughters, Jada and London, and one son, Mitez. Partners with the Humane Society to help educate and steer children away from animal cruelty after his incarceration in a federal prison for involvement in a dogfighting ring.

Career: Former top overall pick of the Atlanta Falcons is a four-time Pro Bowl selection who signed with the Eagles in 2009 after an NFL suspension. Has 18,229 career yards, 113 touchdowns and 76 interceptions. All-time NFL leader for rushing yards among quarterbacks with 5,251 yards.

Recent history: Last season, Vick set career records for attempts (423), completions (253) and yards (3,303) as he threw 18 touchdown passes with 14 interceptions. In 2010, Vick passed for 3,018 yards and a career-high 21 touchdowns with a career-best 62.6 percent accuracy and only six interceptions.